Compensator for ordnance



April 5, 1938. R. M. cUT'rs, JR 2,112,831

GOMPENSATOR FOR ORDNANCE Filed Dec. 7, 1955 2 Sheelzs-Sheecl l FIG. El.

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RM. E u TTBM April 5, 1938. R. MQ cUT'rs. JR 2,112,831

CoMPENsAToRVFoR ORDNANCE Filed Dec. '7, 1955 2 Sheets-Sheet 2 RMEUTTSJdwg Patented Apr. 5, 1938 uNlTED STATES PATENT OFFICE 15 Claims.

This invention relates to compensators for ordnance and has for itsobject to provide a construction more eilicient in use and less costlyto manufacture than those heretofore proposed.

With these and other objects in view the invention consists .in thenovel details of construction and combinations of parts as will be morefully hereinafter disclosed and particularly pointed out in the claims.

Referring to the accompanying drawings forming a part of thisspecification in which like numerals designate like parts in al1 theviews,-

Fig. 1 is a diagram illustrating in substantial vertical cross sectionthe construction of a compensator employing the principles of thisinvention;

Fig. 2 is a view similar to Fig. 1 but in which there is provided aseries of compensator chambers disposed within an enclosing supplementalcompensating chamber;

Fig. 3 is a view similar to Figs. 1 and 2 but illustrating amodification of the construction shown in Fig. 2;

Fig. 4 is a substantial vertical cross sectional view illustrating amodication of the construction shown in Figs. 2, 3, 8, 9 and 10;

Figs. 5, 6 and 7 are substantial vertical cross sectional viewsillustrating modifications of the constructions shown in Figs. 3, 8, 9and 10;

Figs. 8, 9 and 10 are substantial vertical cross sectional viewsillustrating modifications of the construction shown in Fig. 3; and

Figs. 11 and 12 are respectively vertical sections taken longitudinallyand transversely of a further compensator modification wherein all ofthe compensator chambers are substantially coaxial Within their lengths,Fig. 12 being a view taken as on the broken line I2-I2 of Fig. 11 andlooking in the direction of the arrows.

According to Fig. 1 there is provided an outer chamber I threaded orotherwise secured to an integral portion 2 of the gun which may be themuzzle end of the jacket of a machine gun. The forward end of thischamber is shown tapered as at 3 to provide an orifice l of a diametersuicient to permit the projectile from the gun barrel 5 to passtherethrough. Within this outer chamber is a second chamber 6 secured atone end to the gun barrel, which may or may not be reciprocatory, andhaving its other end forwardly tapered as shown at 1 providing anorifice 8 also adapted to permit passage therethrough of the projectilefrom the barrel. The chambers I and 6 may conveniently be made similarto those disclosed in prior known constructions and generally consist ofa metallic wall in which are formed a plurality of narrow slots orapertures for egress of the gases of explosion accompanying theprojectile.

These slots are substantially parallel to each other and formed asindicated at 9 in the portion of the wall of chamber I above thehorizontal axial plane thereof, said slots extending in spaced relationrearwardly of thev chamber to a point slightly back of the middlethereof. There may also be provided a plurality oi similar slots I0 inthe forward tapered portion 3 of this chamber. Slots II and I2 areformed in the inner chamber wall 6 similar to the slots 9 and I0, exceptthat the slots II and I2 are preferably disposed on the sides of saidchamber leav- 15 ing the extreme top and bottom wall portions of saidchamber imperforate. Also, the slots II and I2 are preferably disposedin transverse planes of the inner compensator chamber, intermediatesimilar planes passing through the slots 9 of the outer compensatorchamber, so that 20 the gases leaving the combined compensator structurewill not have a straight path to the outside atmosphere, but in passingfrom the slots II and I2 said gases will impinge upon imperforate wallportions of the outer compensator chamber and then have to travellongitudinally of the device to reach and pass through the slots 9. Informing the slots 9, I Il, II and I2, the cutting tool may be actuatedin a plane forming with the axis of the compensator chambers, or it maybe actuated in a plane making a different angle to said axis, accordingto whether the particular gun to be tted with the compensator would haveits action improved 35 by a rectilinear or oblique emission of gasesthrough the slots. It will be understood, of course, that the twocompensator chambers I and 6 will be coaxially mounted and that thediameters thereof will be sufficient to create a material space betweenthe walls of said chambers.

In the form of the invention illustrated in Fig. 2, there is providedthe same integral gun portion 2 and barrel 5 as described above, but theouter compensator is made of an increased length over that shown in Fig.1 to accommodate a plurality of serially connected inner compensatorchambers. That is to say, the outer compensator I5 has its rear endrigidly attached to the sleeve or other gun mounting 2 and has itsforward end provided with substantially the same forward tapered portion3 as above described except that the orifice 4 heretofore described isin Fig. 2 shown internally threaded to receive the forward end of animperforate tube I6 whose rear end is adapted to have a somewhat tightbut sliding fit upon a forwardly extending tubular neck I1 of anintermediate inner compensator I8 whose opposite or rear wallthreadingly receives the forward end of the tapered portion 1 of therear inner compensator I9. The rearmost end of this compensator I9 isadapted to have a somewhat tight but sliding iit over the extreme end ofthe muzzle of the barrel 5, and when the parts are assembled as shown inFig. 2 it will be seen that the outer compensator I5 is of a lengthsufficient to cover the serially connected parts I6, I8 and I9 with therear end of the member I9 jammed against the end of the gun mounting 2,it being understood that the inner compensators I8 and I9 as well as thetube I6 are uniaxial with respect to each other and coaxial with respectto the outer compensator I5. The two inner compensators I8 and I9 areprovided with respective slots 20 and 2| similar to each other andlikewise similar as to placement to the slots II shown in Fig. 1, andthe tapered portion 1 of the rear inner compensator I9 is likewiseprovided with slots 22 similar to the slots I2 of said Fig. 1.

The outer compensator I5 may be said to have slots similar to the slots9 and I0 of Fig. 1 in that they are similarly formed and spaced, butthey do not extend rearwardly beyond the intermediate inner compensatorI8, thereby leaving a material portion of the wall of the outercompensator imperforate all around against which the gases emerging fromthe rear inner compensator may impinge. 'I'he slots 20 of theintermediate compensator may be in registry or not with the slots 9 ofthe outer compensator, it being shown in the drawings that the middleslot 20 is in registry whereas the other two slots have staggeredrelation with the slots 9 of the outer compensator.

'Ihe inner diameters of the rear and intermediate inner compensators aremade substantially equal whereby it will readily be seen that thecylindrical portion of the rear inner compensator constitutes anexpansion chamber for the gases of explosion as they emerge from themuzzle of the barrel 5 since said compensator nts over the exteriorsurface of the barrel and hence must have an inner diameter greater thanthe bore of the barrel. It will also be readily apparent that theseexpanded gases will be compressed in passing over the slopes of thetapered portion 1 of the said compensator and when the gases enter theintermediate inner compensator I8 they will be permitted anotherexpansion to fill the interior space thereof, but upon leaving thecompensator I8 the gases will be restricted in passing through thereduced or neck portion I1 at the forward end thereof which neck has aninternal diameter substantially equal to the internal diameter of thepassage between the compensators I8 and I9, and that upon emerging fromthe neck I1 the gases will be permitted slight expansion inthe forwardtube I6.

In Fig. 3 there is also disclosed a plurality of serially connectedcompensator chambers, with an outer compensator enclosing a portion ofone and all of another of the serially connected compensators. In otherwords, similar reference numerals have been given to parts similar tothose hereinbefore described, but the intermediate inner compensator 25differs from the intermediate inner compensator I 8 shown in Fig. 2 inthat its cylindrical portion is extended rearwardly, ending as at 2B inclose proximity to the foremost position of the reciprocable barrel 5 ofa machine gun, for example, and when the structure of Fig. 3 is used inconnection with guns without a reciprocable barrel, the space betweenthe muzzle of the barrel and the end 2B of the compensator 25 will berelatively small so that the majority of the gases of explosion mayenter the compensator 25 under substantially full velocity. Theshoulders formed at the forward end of this compensator will, however,impede the forward drive of these gases and build up a pressure in thecompensator suflicient to augment somewhat the lateral dispersion fromthe axis of the device through the space just referred to and cause suchdispersed gas to enter the rearmost compensator generally identified bythe numeral 21. This rearmost compensator 21 is threaded to the gunmount 2 and has a cylindrical portion extending forwardly toapproximately the foremost throw or movement of the gun barrel if thelatter is reciprocable, and it then tapers inwardly and forwardly asshown at 28 with its foremost end screw threaded externally on theintermediate compensator 25.

A plurality of apertures 29 are provided on the tapered portion of therearmost compensator to permit the gases therefrom to enter the spacebetween the intermediate compensator 25 and the foremost outercompensator 30 which latter has its rear end threaded externally on therearmost compensator 21 and is similar in other respects to thecompensator I5 shown in Fig. 2. Here again the slots 20 of compensator25 may or may not be in registry with one or more of the slots 9 of theouter forward compensator 30, and it will be clearly observed that thecompensator 30 encloses all of the intermediate compensator 25 and thetube I6, as well as the tapered apertured portion 28 of the rearmostcompensator 21, with all compensators arranged coaxial with respect tothemselves and the axis of the gun barrel.

In Fig. 4 is shown a modification of the construction shown in Figs. 2and 3 and according to this modication the outermost forward compensatorinstead of being forwardly and inwardly tapered, is of the samecylindrical formation as indicated at 35 as the main body portion. Toprovide a restricted forward end of this compensator chamber, the tubeI6 is, in this modification, provided with a divergent forward taperindicated at 36 with its outermost end screw threaded to the outer endof the compensator wall 35, the tapered portion 36 being provided with aplurality of apertures 31 to permit passage of gases therethrough aswell as relief of pressure from the chamber of the outermostcompensator. 'I'hus it will be seen that this construction issubstantially a reversal of that shown at the end of the deviceillustrated in Fig. 2.

The construction according to Fig. 5 is a modification of that shown inFig. 3, for example, wherein the intermediate compensator 25 and thetube I6 of the latter have been combined in an elongated cylindricalinner compensator 38. Also the slots 9 of the hereinbefore mentionedouter compensator have been omitted from the similar counterpart 39constituting the outermost compensator of this modification, and theforward taper of this compensator is herein provided with a plurality ofapertures 40 for egress of the gases in place of the slots I0 of theform hereinbefore described. On the other hand, the imperforate tube I6is in this modification supplanted by an extension of the intermediatecompensator, with slots 4I provided in its side portions. Substantiallythe only other principal difference resides in the provisionl of taperedshoulders 42 at the forward end oi' this modified intermediatecompensator 88, ending in an oriilce 48 oi' reduced diameter andsomewhat similar to the portion I1 of the corresponding compensator 25shown in Fig. 3. The shoulder 42 has somewhat the same effect upon theforwardly moving gases as the shoulders shown in Fig. 3 on thecompensator chamber 25. In conclusion it might be observed that the rearend of the forward outer compensator 39 is not threaded to the rearcompensator 21 but when the Darts are screwed together this joint willbe substantially gas tight, and the slots 20 are disposed in theintermediate compensator 88 to permit gases to pass therethrough intothe conilnes of the compensator 21.

'I'he modication according to Fig. 6 shows a construction similar toboth Figs. 3 and 5 and similar reference numerals represent similarparts. 'Ihat is to say, the diierences are that the walls of thecompensator.39 of Fig. 5 are apertured in accordance with the showing inFig. 3, and the slots 4| of the compensator 88 shown in Fig. 5 have beenomitted.

According to Fig. 7 the construction of the compensators 27 and 30 shownin Fig. 3 have been duplicated but the tube i8 has been omitted andsupplanted by an elongation of the intermediate inner compensator shownin said ngure. In other words, this said intermediate compensator 45 inthis modication has been extended to the forward end of the outercompensator 30, is substantially cylindrical throughout its length andprovided with a forwardly inclined or tapered shoulder 46 substantiallyidentical with the similar shoulder 62 shown in Fig. 6 except that theshoulder t6 is spaced inwardly from the muzzle of the outer compensatorquite an appreciable distance so that there is formed an irnperforateforward wall portion of the compensator 45 disposed opposite nearly allof the slots 9 and i0 of the outer compensator tu. The slots 20 of thisinnermost compensator are disposed substantially the same as thecorresponding slots of the compensator 25 shown in Fig. 3, and theremainder of the construction is identical with said Fig. 3 except thatthe threaded joint shown in said gure between the compensators 2'! and35 is replaced by the tight slip joint shown in Figs. 5 and 6. y

The construction shown in Fig. 8 diers from that shown in Fig. 3 in thatthe slots 28 of the latter are replaced by slots 41 disposed in theupper portion of the wail of the intermediate inner compensator 25, andthe slots 9 and i8 oi' said Fig. 3 are replaced respectively by theslots 48 and 49 disposed in the sides o1' the outer compensator 30.Additionally it is to be particularly observed that according to thismodiilcation there is always an imperforate wall section of onecompensator opposed to any slot or other opening in another of theassociated compensators.

According to Fig. 9 there is a slight departure from the constructionshown in Fig. 8 and residing in the fact that the innermost compensator25 is herein provided in both its top and bottom wall ysurfaces withslots 50 of the type shown at 41 in Fig. 8, and the rear outercompensator 21 is joined to the innermost compensator 25 by a tapered orconical wall 5I having a slope which is the reverse of the correspondingpart 28 in Fig. 8, but otherwise provided with the similar apertures 29.

The modiiication according to Fig. 10 shows an inner intermediatecompensator 25, substantially a duplicate of that shown in Fig. 3, aswell as outer end compensator 30, also substantially identical with itscounterpart shown in said iigure. However, the outer rear compensator 21is formed similar to its corresponding compensator shown in Fig. 9 withthe exception that the rearwardly and inwardly tapered wall 5I of thelatter figure is replaced in this gure by an imperforate wall 52 whoseinnermost end is spaced slightly from intermediate compensator 25 asindicated at 53, thereby leaving a circumferential passage between 25and 52.

Whereas in Figs. 2 to 10 inclusive there has been illustrated a'seriallyconnected compensator structure, in Fig. 11 there is shown a combinationof coaxial compensators based upon the principles ot theA constructionshown in Fig. 1. with Fig. 12 representing a vertical sectional viewtaken at right angles to the axis of the device shown in Fig. 11. Forconvenience in illustration the compound compensators of thismodification are shown attached directly to the muzzle end of the barrel5 but it will be understood that they could as Well be attached to otherportions of the barrel mount. According to this modification theinnermost compensator 55 comprises a substantially cylindrical chamberthreaded at the rear end to the barrel and having its forward endextended at a reduced diameter to provide a tube portion indicated at 5Sand threaded externally at its outermost end to receive thereon a nut 5lor other suitable element for securing sealing material indicated at 58for closing the 'joint between the innermost compensator and theoutermost. The opposite side walls of the rear cylindrical portion ofthis innermost compensator are provided with spaced slots indicated at59. Prefeiably threaded to the rear end of the innermost compensator isthe rear end of the intermediate compensator d of substantialcylindrical formation whose forward end terminates in an inwardlydirected shouldered closure Si adapted to slidingly nt the exteriorsurface of the tube portion 56 of the compensator 55, with the top andbottom wall portions of this intermediate compensator provided with aplurality of spaced slots 62 preferably disposed in staggered relationwith the slots 55 of the compensator 55. The slots 82 may be in numbersuilicient to extend forwardly of the foremost slot 59 as clearlyindicated and therefore it may be said that substantially the entirelength of the intermediate compensator is thus provided with slots.

In a similar manner the outermost compensator 63 is threaded at its rearend to the rear end of the intermediate compensator, the formerexltending forward to entirely enclose said intermediate compensator,with the extreme forward end 84 of rthe outermost compensator somewhatsimilarly formed to provide a shoulder and sliding fit upon the outersurface of the tubular portion 58 of the innermost compensator, thesealing material 58 being disposed between the end of the outermostcompensator and the nut 51. Thus it will be seen that the threecompensators 55, S0 and 63 are coaxial and have their substantiallycylindrical walls disposed in concentric but spaced relation from eachother, the side walls of the outermost compensator being provided with aplurality of slots 55 staggered with respect to vthe positioning of theslots 52 of the intermediate compensator, and each compensator providedat its forward end with a shouldered portion against which the force ofthe gases may impinge or be the outer surface of the t directed in aneffort to counteract recoil, whereby the gases in emerging from thebarrel will be caused to move first through the slots 59 of theinnermost compensator, thence through the slots 62 of the intermediatecompensator 60 and nally through the slots 65 of the outermostcompensator to gain the atmosphere, this path being Atortuous andoccasioned by the pressure and velocity of the gas and itstemporarvconiinement by the sealing of the bullet in the tubular portionof the innermost compensator.

In order that this invention may be better understood, attention isdirected to U. S. Letters Patent No. 1,605,393, No. 1,636,357 and No.1,773,260 granted respectively on November 2, 1926, July 19, 1927 andAugust 19, 1930 to Richard M. Cutts and Richard M. Cutts, Jr. anddisclosing compensator devices adapted for attachment to the muzzle ofguns of various calibers and powers for the purpose of overcoming climband reducing recoil. However, in service and in actual operation ofthese devices certain minor factors appeared which were to a certainextent undesirable, and there were certain undesirable effects developedby the operation of these structures, and which were inherent to the useof these devices, and therefore this present applicationvcovers devicesvwhich will have increased efficiency over the structures of saidpatented devices and which additionally overcome the undesirable factorsreferred to above, this application covering a combination in fltting ofdevices, and application of the forces developed, to various parts ofthe gun h structure.

In other words, it was disclosed in said patents how the gases ofexplosion, as they emerged from the barrel muzzle, were permitted firstto expand due to the increased internal diameter of the expansionchamber portion of the compensator, and then the pressure of said gaseswas increased when the forwardly moving gas column impinged upon theinner surface of the tapered portion of the compensator termed thecompression chamber, the latter action resulting in the creation of afriction having the characteristic of a blow imparting a forward driveto the entire firearm overcoming an appreciable amount of the normalrecoil. Further, it was disclosed how the apertures in the wall of thecompensator were designed to permit the escape of most of the gas underits increased pressure, and that the imperforate wall opposite saidapertures received the force of the expanding gases resulting in atransverse movement of the compensator in a direction opposite to thegas escape through said apertures. 'I'hese same functions and principlesare likewise existent in the present invention and therefore the precisedescription and development of these actions will not be given in detailsince the similarity of chamber construction to that disclosed in saidpatents is readily apparent.

It is desired to point out that the term "compensator" has now beenaccepted by the military branches of the U. S. Government, as well as bythe purchasing public asV defining a device for attachment to a gunmuzzle which is provided with one or more chambers adapted to receivethe gases of explosion and to act upon said gases in manners to overcomethe climb tendency as well as to reduce the recoil of the weapon.'Iherefore, in the claims this word compensator will be understood tohave this meaning.

Various arrangements and forms of slots are disclosed in the abovementioned patents, and therefore it is not desired to be limited to thetypes and arrangements of slots disclosed in the accompanying drawings.A change in this form and arrangement would be evident to anyone skilledin the art.

It will be understood that every gun has its own individualcharacteristics, every type and caliber of shoulder gun, automatic andsemi-automatic rifles, machine guns, submachine guns, Shotguns, andmajor ordnance, requiring the flexible application of power of thedevices covered in said patents, the present application covering thedevices necessary to overcome undesirable factors developed in theapplication of compensators to any of these mentioned or other guns,under various load conditions, in addition to other matters set forthhereinafter.

In many machine guns, the recoil of a reciprocating barrel is used tooperate the mechanism of the gun. In high power guns the recoil power ofthe reciprocating barrel is far greater than is necessary for operatingthe mechanism,v thereby creating strains and impact blows in theoperating mechanism which are highly detrimental to its longevity, andpositiveness of continued operation. As seen clearly in Fig. l an innercompensator 6 may be fitted to the reciprocatory barrel 5, thiscompensator to be of such graduated value in reduction of recoilas topermit enough recoil of the reciprocating barrel to insure operation ofthe gun mechanism, while negativing the remainder. Under theseconditions the design of the inner compensator cannot be of such valueas to apply its full powers of recoil reduction to the reciprocatingbarrel, for if it were then the gun would not operate successfully. Byattaching an outer compensator l to the gun jacket or muzzle gland 2,that part of the possible recoil value in the inner compensator 6 winchmust be sacrificed to insure the operation of the gun mechanism, isrecovered and applied to the general recoil reduction of the entire gun,at the same time realizing and utilizing the increased values of thecombined inner and other compensator construction.

This invention includes the principles disclosed in said patents, butadds to the novelty thereof in that the devices made in accordance withthis invention will, more specifically (1) increase the recoil reductionover the devices of said patents; (2) reduce the undesirable concussion,or report, produced by the action of the said patented devices, undercertain circumstances; (3) hide the normal muzzle flash of guns, evenwhen the latter have unbalanced loads, as well as conceal the muzzlefiash which under certain circumstances is augmented by devices,designed according to said patents, when certain gunpowder and loadconditions are present; and (4) permita new application of the power,developed by the devices, to separate parts of the gun structure.

In general the power of the muzzle blast of a gun lies in the velocityof the gas, and the pressure of that gas; the pressure of the gas is ofbut little use normally owing to the existing velocity, and the greaterthe velocity the less the availability of the pressure for use in anycircumferential or radial direction. In the patented devices the twodistinct power elements existing in the muzzle blast are reacted intoone usable force. The velocity is checked and expended in acounterrecoil action; the reaction of the checking of the head of thecolumn of gas resulting in a very great increase of usable pressure andthe production of great heat at the point of impact of the gas column.Lateral expansion of a circumferential or radial nature is nullilled bythe walls of the expansion and compression chambers of the device. Theresult is a building up of very high usable pressure in the expansionand compression chambers, and by porting the expansion and compressionchambers as described in the aforementioned patents, this pressure maybe used in direct or compound reactions to overcome or produce movementsof the muzzle and an additional recoil reduction other than that causedby the arrestation of the forward velocity of the gas column.

It will be understood that the porting must always be of sufficient areaand capacity to discharge the built-up, gas pressure in the desireddirections before this pressure can materially raise the muzzle pressureof the gun and travel back into the bore. The pressures generated arequite high, owing to theifact that the impact of the gas is as thesquare of its velocity; gas being compressible, the rebound from thisarrestation is directly against the velocity of the rest of the oncomingblast. Ballistically speaking the time element of the application ofthis power is considerable and affords ample time for its absorption anduse. Actually, this is the same power development which causes a slightobstruction in a barrel to swell or burst the strongest gun, althoughthe obstruction at no time causes but a slight arrestation of theforward velocity of the gas. The strength of the expansion andcompression chambers must be sufficient, in coordination with theporting area, to resist rupture, and therefore the porting area iscalculated to prevent an undue rise in pressure.

As may be deduced from the above, and is conrmed by many sparkphotographs, the greatest pressure in the patented devices exists at theforward end of the device, the pressure decreasing rapidly toward therear of the device as it approaches the gun muzzle. With powderproducing some smoke, gas at a very high velocity can be seen in saidphotographs as issuing from the ports, as would be expected, resultingfrom. the building up of pressure by the reactions. Such photographsshow a high velocity of this gas as measured in distance travelled incomparison with the known velocity of the projectile which appears onthe same negative, and in said photographs with guns of high power, theemission of the gas particularly from the front end ports of thepatented devices, carries a heavy compression wave in the opposing airwhich, when the gas velocity is reduced by air resistance to the speedof sound, becomes a sound wave; this sound wave is proportional inintensity to the blow delivered by the speed of the gas discharge, suchdischarge by the 'ports being in a more or less lateral or radialdirection to the axis of the gun bore, wherefore this sound wave reachesthe gun rer in high intensity, and is highly disagreeable except in gunsof low power.

(l) Increase in recoil reduction-It has been found that the gas, issuingfrom the ports of the patented devices, has more power and velocity thanis necessary in medium and high power guns to overcome climb, and it hasbeen found necessary to so direct and position these ports that theirfull value is not used, for otherwise an unwanted down drive of themuzzle will occur; this excess power can not, with the patented designsin question, be used in further reduction of recoil; the excess powertherefore passes out into the air and is wasted. y

In the devices covered by this\application, a gas blast of suiiicientveocity and power is emitted in the desired direc ion to overcome theclimb of the gun,y and the extra power is retained in the device andused in further reduction of recoil. Particularly in Figs. 2 to llinclusive it will be seen how this is accomplished, for the gas leavingthe barrel isdirected into the rst inner compensator chamber inprolongation of the barrel, and from this chamber it passes into theintermediate or next compensator such as those indicated by the numeralsI8, 25, 38 and 45. However, it will be observed that these intermediatechambers just mentioned have their forwards ends formed with a reductionin diameter at the outlet thereof, which outlets are identied by thenumerals l1, and 43, and also the tube 56 shown in Fig. 1l; thereforethe forward directional drive of the gas blast impinges directly uponthe shouldered portions associated with these outlets, resulting in whatmight be termed a forward blow, and this is in addition to the forwardcounterrecoil action resulting from the initial impact of the gas columnon the tapered slopes of the first compensator chamber into which thegas passes, such slopes being indicated by the numerals 1, 28, 5I and52. With particular reference to Fig. 11, the initial impact of themoving gas column upon leaving the muzzle is directed upon theshouldered and reduced end portion of the innermost chamber 55,

but because the tubular portion 56 has comparative length, the bulletpassing therethrough will establish a seal for a longer time than waspossible in the case of the patented constructions referred to, andtherefore the effect of the forward drive, initiated by the impact ofthe gas column, is prolonged. It will be understood that whereas thevarious apertures are herein shown as substantially formed at rightangles to the axis of the barrel, they may be formed obliquely theretoas shown in the patents referred to, in order to augment thecounterrecoil action.

(2) Reduction of report-Owing to the building up of high pressure in thepatented devices the gas is discharged directly into the air at quitehigh velocities, the gas carrying a heavy compression and sound wavewhich is objectionable as stated. On the other hand, as will be seenfrom the drawings, in the devices covered by this application, the gasis not discharged directly into the air but is made to travel throughone or more chambers, finally being ported from the outer compensatorchamber at comparatively low velocities and pressure, the counterrecoilaction absorbing some of the excess power, and the'expansion and coolingof the gas while passing through the serial chambers being responsiblefor further reduction in velocity and pressure. Sufficient power only isused with the lower pressure emissions to overcome the climb, thecompression wave and sound wave therefore being much reduced in power,and this reduced wave is delivered in a generally radial direction fromthe axis of the gun bore, decreasing the intensity of the reportdelivered by the patented devices. All of the figures of drawingsclearly show this effect of the escapement of the gas through thevarious compensator chambers before reaching the atmosphere, andtherefore the above action can be fully appreciated.

(3) Hiding of normal muzzle flash-The amount of muzzle ash of guns isdependent upon the amount and type of powder used in relation to thevolumetric capacity and cooling eifect of the barrel, as well as thelength of the barrel. The muzzle flash oi' a gun with a normal wellbalanced powder load may be slight; if the barrel is shortened with thesame powder load, the flash will be increased; and if the barrel islengthened suiciently the flash will decrease to complete disappearance.The factors of quick and slow burning powders in the same gun havedenite eects on muzzle ash, as well as the time taken by the bullet totraverse the barrel. With the normal gun barrel the flame of burninggases is immediately projected into the air, and immediate and rapidexpansion and cooling takes place lowering the temperature below thecombustion point in an exceedingly short time. The greater the volume ofburning gases, the greater the muzzle ash in consequence. With one ofthe patented devices secured to the muzzle, the burning gases at the gunmuzzle do not meet the same conditions for rapid expansion and reductionof pressure, owing to the interposition of the expansion andrecompression chambers of the device and a definite increase in pressureand heat in the forward end of the devices as before explained, inconsequence of which the muzzle ash of burning gases is not sufficientlyand immediately cooled below the combustion point, and may extend intoand issue from the ports of the patented devices. rendering thedischarge of the gun quite visible at night, particularly with a loadnot well balanced. In the devices covered by the present application,such ame is emitted into the second chamber where expansion and coolingtake place very rapidly, and the gas is below the combustion point whenit emerges from the ports of the farthest chamber, with no flame showingat these ports.

A gun usually contains more powder than is capable of being burned inthe bore during the time that the projectile is passing therethrough,particularly with the progressive burning powders now so generally inuse. In consequence partially consumed and at times unburned grains ofpowder are ejected into the atmosphere at the gun muzzle, and sincethese powder particles have a high velocity, they are extinguished whendriven through the atmosphere, and therefore they do not completelyburn. 'I'his effect is clearly demonstratable and proved through the useof spark photography. The amount of this unburned powder in small armsis not great, but it is variable. On the other hand, it is a matter ofcommon knowledge that after big gun practice on a battleship the deckscontain considerable drifts, sometimes several inches deep,

of partially consumed powder grains that have been extinguished andblown back upon the deck.

In a gun tted with one of the patented de# vices referred to, theseunburned powder particles traverse the expansion chamber but are checkedin the recompression chamber in the same manner as the forward velocityof the gas is checked, and at this point the reaction of the checking ofthe velocity of the head of the gas column against the oncoming gasraises the pressure and creates heat, thereby restoring conditions whichpermit the powder to burn. Thus there is generated within such a device,heat, pressure and gas, the flame of which would appear and bedischarged through the forward ports of such devices. In the devicescovered by the present application, this discharge is into the spaceenclosed by the outer compensator chamber wall, where suiiicientexpansion and cooling take place to obviate ame discharge from the portsin said outer wall.

In connection with this hiding of the flash, it is desired to point outthat the present invention embodies a. design of construction permittingmore oxygen to be present during the combustion of the gases within thedevice than with the patented devices. It is understood that powdergenerally speaking has the necessary oxygen within the powder mixture tosupport combustion, but this is not entirely true inasmuch as that, withpresent day machine guns when firing rapidly, an explosive mixture orpowder dust is emitted from the muzzle of the gun and hangs in the air.This mixture is ignited occasionally by burning gases, causing what isknown as a iash bomb. 'Ihis is particularly true with large caliberanti-aircraft machine guns.

By increasing the volumetric capacity of the compensators as shown inthe accompanying drawings, there is more oxygen present in thecompensator chambers during the final combustion of the gases at thetrue muzzle of the gun. This in conjunction with the valving down of thegases from one compensator chamber to 'the other, through multipleports, gives reduced flash. Moreover the reworking of the gas throughthe multiple compensator chambers gives increased eiiciency.

(4) New application of poulet-The slots or ports according to thisinvention may be arranged either according to thoseshown in the abovemetioned patents or otherwise, as exigencies may demand. It will beunderstood that the arrangements of the ports determines the down driveeffect which varies with every type of gun tted. In some cases it isquite possible owing to line of mount recoil resistance in relation toline of recoil action, that no down drive will be desired since thereduction in recoil will in itself be sufficient to reduce or eliminateany upward climb of the gun. In such cases the porting arrangement willbe as shown in Figs. 5, 9 and 11 or some simple modication thereof. Themodifying factor under these circumstances is that the ports arearranged diametrically opposite each other in equal numbers, so that therelease of the gas is equalized. It is understood that if the release ofgas is not equalized, a positive motion is given to the compensator andby means thereof to the gun in a direction away from the point ofgreatest gas release. From the above it will be understood that theactual arrangements of the ports will vary depending upon the particulargun to be fitted and the exigencias which have to be met, and in viewthereof it is not desired to limit this invention to any exactdisposition of the ports, since it has been found from practice thattheir location is a variable factor.

It is conceivable that the form of compensator shown in the abovementioned patents may be used in conjunction with a flash hider to coverthe flash. 'I'he present form of hider consists merely of an imperforatetube secured around the muzzle of a gun and extending forwardlytherefrom, the tube tending to cover the pencil of ame as it emergesfrom the muzzle. However, due to practical reasons, such a tube cannotbe made sufficiently long to fulfill the purpose -for which it isintended, with the result that in present practice the flash extends forsome distance beyond the end of the tube.

The ash hlder in and of itself has no function in regard to reducing therecoil of the gun. A combination of a iiash hider with one of thecompensators shown in the patents referred to but fitted therein, wouldgive the recoil reduction advantage oi one compensator plus a partialash concealment. On the other hand, by the present invention additionalrecoil reduction is accomplished, and complete concealment of the iiashis eiected,-by the use of the multiple compensator chamber arrangementsshown in the various modifications of the drawings when properly fittedto gun conditions.

The present invention relates to an increasein eiiiciency incompensators by the use of multiple chambers. The gas when released fromthe compensator chamber which first receives it, 'is still at highpressure, and it then enters successively the other compensatorchambers, performing work therein, so that when it reaches theatmosphere, it is at a materially lower pressure than would have beenthe case were it released from the initial compensator chamber directlyto the atmosphere. This action constitutes a valving down of the gaspressure, and it will be understood further that this same valving alsoeifeets a material diminution or elimination of flash.

Volumetric capacities are such that the combustion is more or lesscomplete before the nal emission of the gas to the atmosphere since thiscapacity determines the amount of oxygen present. Moreover, the tortuouspath which the gas must traverse slows its forward movement before itreaches the atmosphere, thus lengthening the time for completecombustion as Well as affording additional time for the absorption ofthe powers delivered. From actual tests by the U. S.' Army on patentedcompensators it has been found that the forward velocity of the gas atthe muzzle of a gun has been reduced from 3500 down to 800 feet persecond with the use of only one compensator chamber as disclosed in theaforementioned patents.

The present invention is directed to the use of one compensator chamberwithin another, either interconnected or not as desired, and inconjunction therewith there is a muzzle tube as shown in Figs. 2, 3, and7 to 11; a modified tube is shown in Figs. 5 and 6. This tube in and ofitself is an increase of efficiency since the gas is practically sealedwithin the compensator from the time that the nose of the bullet entersthe rear end of the tube, to the time that the base of the bullet clearsthe front end of said tube. The length of time that the gas is workeddetermines the amount of energy that may be extracted, and therefore theuse of the tube represents an additional gain in efhciency. This is amatter of record from tests conducted with the use of .45 caliberbullets as well as 9 mm. projectiles.

It is obvious that those skilled in the art may vary the details ofconstruction as well as arrangements of parts without departing from thespirit of the invention, and therefore it is not desired to be limitedto the foregoing except as may be required by the claims.

What is claimed isry 1. An attachment for the muzzle of Vfirearms havinga movable barrel comprising a cylindrical casing adapted to'be attachedto said barrel and constituting an expansion chamber for the gases ofexplosion 'as they leave the barrel, the Walls of said casing beingconically formed at the forward end to provide a compression chamber forincreasing the pressure of the forwardly moving gases, the walls of theexpansion and compression chambers provided with apertures for releasinga portion of the gases under pressure, the remainder of the gasespassing through a projectile opening disposed at the apex oi thecompression chamber, said apertures tormed in diametrical portions ofsaid walls whereby the gases in escaping therethrough tend to counteractrecoil of the firearm; and a second casing iitted to a stationary partof the rearm and disposed in spaced relation about the first namedcasing, the walls of the second casing similarly forming a, cylindricalchamber and a forward conical chamber in prolongation thereof forreceiving the gases Vfrom the rst named casing and similarly treatingthe same, the walls of the second casing provided with gas exitsdisposed to one side of a plane passing substantially through the axisof the second casing thereby leaving imperforate the wall portion on theother side of said plane whereby the gases in escaping through saidexits will exert a pressure against the imperforate portion of thecasing wall to produce a movement of the muzzle in the direction of saidpressure.

2. A compensator for attachment tothe muzzle of firearms and comprisingwalls forming an expansion chamber having a projectile opening at itsforward end, said opening establishing a gas seal with the projectilewhen the projectile is in said opening, said chamber being cylindricalthroughout a substantial portion of its length and receiving the gasesof explosion as they emerge from the muzzle; means to gradually increasethe pressure of the expanded gases, said means comprising portions ofthe chamber walls conically tapered from the cylindrical portion to saidopening to direct the forwardly moving expanded gases to and throughsaid opening; a second walled chamber to receive the gases from saidexpansion chamber; and means to release the expanded gases underpressure to produce movement of the muzzle in a predetermined direction,said means including gas conducting passages between said chambers, andgenerally opposite imperforate wall portions thereof.

3. An attachment for the muzzle of firearms4 having a barrel movablewith respect to the rest of the firearm, said attachment comprising apair of substantially cylindrical chambers connected serially for gascommunication, the rearmost chamber fitted at one end upon the movablebarrel for slidable relation therewith, the other end of said chamberhaving its walls forwardly converged, the forward chamber fitted at oneend upon the reduced end portion of the rearmost chamber and having itsother end fitted with a projectile tube, the internal diameters of themain b ody portions of said pair of chamsaid third chamber secured atits rear end to a stationary portion of the firearm and having its wallsforwardly converged at its front end and supporting said projectiletube, and gas ports in the walls of all of said chambers, the ports of gtion thereof opposite the ports of said rearmost chamber. Y 4. Anattachment for the chambers, a rearmost chamber 4secured kto the firearmmount in substantially coaxial relation with the barrel of the weapon`and having the walls at its front end forwardly' .converged andsupporting an intermediatechamber, the walls of said intermediatechamber extending both forwardly and rearwardly vof its pointw'ofVsupport whereby a portion of the intermediate chamber lies within therearmost chamber, thexwallsr of the forward end of theinteririediatei'chamber` being inwardly directed" and terminating in aprojectile passageY having a` projectile -K tube extending forwardlytherefrom,l a third chamber secured to the 4rear/most chamber and havingits walls in prolongation'bf the walls of the" main body portion ofvsaid rearmost chamber, said third chamber encompassing a portion ofsaid rearmost chamberv and substantiallyall of said intermediatechamber, the walls of the front end of said third chamber beingforwardly'converged and supporting said projectile tube, gas ports inthe converged walls of said rearmost chamber for conducting expandedgases of explosion directly into the third chamber, said ports opposedto an Vimperforate wall portion of said third chamber, and gas ports inthe forward portions of said intermediate and third chambers.

5. AV compensating device for attachment to the muzzle of firearms andto receive the gases of explosion issuing therefrom, said devicecornprising a pair of serially connected and coaxial chambers as well asa third chamber encompassing portions of the pair of chambers, all ofsaid chambers being substantially cylindrical and having a projectileopening at an end thereof, said chambers also having gas conductingpassages therebetween, the walls at the forward end of the encompassingchamber as well as the forward wall portion of one of the chambers ofthe pair of chambers having a conical interior surface extending fromthe cylindrical portion forwardly and inwardly to said opening toincrease the pressure of the forwardly moving gases.

6. An attachment for the muzzle of'ilrearms comprising a pair ofsubstantially coaxial charnbers one in advance of theother, one of saidchambers receiving the gases of explosion from the barrel, a thirdchamber encompassing portions of the pair of chambers, all of saidchambers having gas conducting passages therebetween, the gases ofexplosion passing unobstructedly from the gas-receiving chamber throughits apertures into an imperforated portion of the encompassing chamberand .then passing unobstructedly through the apertures of theencompassing chamber directly into the atmosphere, the walls at theforward end of the encompassing chamber as well as the forward wallportion of the gas-receiving chamber having a forwardly and inwardlydirected conical interior surface to receive the blow of the forwardlymoving gases and thereby counteract the recoil of the rearm, theapertures of the encompassing chamber disposed in a substantiallengthwise portion of its wall as well as in substantially one-half ofthe circumferential wall portion thereof leaving the remaining wallportion opposite said apertures imperforate whereby the gases inescaping through these apertures v muzzle' of firearms comprising threesubstantially cylindrical coaxial willexert a pressure against theimperforate wall portion tending to produce a movement of the muzzle inthe direction of said pressure.

7. An attachment for the muzzle of rearms having a barrel movable withrespect to the rest of the firearm and comprising two substantiallycoaxial chambers, one of said chambers attached tov said barrel to movetherewith and receiving the gases of explosion thereform, said chamberhaving gas outlets in its walls adapted to counteract recoil of thefirearm when the gas passes therethrough, the other chamber attached toa stationary portion of the rearm and free of contact with the movablechamber and receiving vthe gases of explosion from the movable chamber,said other chamber having gas exits in its Walls as well as anappreciable imperforate wall portion opposite thereto adapted to producea predetermined movement of the muzzle of the firearm when the gaspasses through said exits.

8. An attachment for the muzzle of a flrearm provided with a barrel,comprising two substantially concentric chambers secured to portions ofthe firearm and adapted to have relative movement one to the other, thewalls of said chambers free of `contact with each other, one of saidchambers receiving the gases of explosion from the barrel, said chamberhaving gas outlets adapted to counteract recoil of the rearm when thegas passes therethrough, the other chamber receiving the gases ofexplosion from the flrst mentioned chamber, said other chamber havinggas exits as well as an appreciable imperforate wall portion oppositethereto adapted to produce a predetermined movement of the muzzle of thefirearm when the gas passes through said exits.

9. An attachment for the muzzle of firearms and for receiving the gasesof explosion after leaving the muzzle, comprising two coaxial chambersone within the other, each chamber termiv nating in a projectileopening, the walls of said chambers provided with gas exits so disposedthat the gases within the inner chamber after passing through its gasexits must traverse the space between the walls of the two chambers inorder to pass through the exits of the outer chamber, said chambersmounted for relative movement one to the other upon firing of theweapon, the gas exits of one of said chambers so formed that thepressure of the gases passing therethrough will counteract recoil, theother chamber provided with a substantial imperforate wall portionopposite its gas exits whereby the gases in escaping through the latterwill exert a pressure against said imperforate wall portion tending tomove the muzzle in the direction of said pressure. I

10. A compensating device for attachment to the muzzle of firearms toreceive the gases of explosion issuing therefrom, said device comprisinga plurality of coaxial chambers, each chamber being generallycylindrical, the forward end of each chamber having its Walls inwardlydirected toward the axis of the chamber and terminating in a projectileopening, the projectile openings of said chambers spaced from each otherlongitudinally of the device and connected by a projectile receivingtube, the walls of each chamber provided with slots for gas escape, eachslot of a chamber disposed opposite an imperforate wall portion ofanother chamber, the slots of the outermost chamber disposedsubstantially above its horizontal axial plane.

11. A compensating device for attachment to the muzzle of rearms toreceive the gases of explosion issuing therefrom, said device comprisinga plurality of coaxial chambers, one chamber attached to a stationaryportion of the firearm and another chamber attached to the barrel tohave relative movement with respect to the first named chamber, eachchamber. being generally cylindrical, the forward end of each chamberhaving its walls inwardly directed toward the axis of the chamber andterminating in a projectile opening, the projectile openings of saidchambers spaced from each other longitudinally of the device, the wallsof each chamber provided with slots for gas escape, each slot of achamber disposed oppositev an imperforate wall portion of anotherchamber, the slots of the outermost chamber disposedsubstantially aboveits horizontal axial plane. l

12. A compensating device for attachment to the muzzle of firearmsprovided with a slidable barrel and adapted to receive the gases ofexplosion issuing therefrom, said device comprising a pluralityofcoaxial chambers, one chamber at- 251 tached to a stationary portion ofthe firearm and another chamber attached at one end to said ilrst namedchamber but slidably supported at its other end on the barrel, eachchamber being generally cylindrical, the forward end of each chamberhaving its walls inwardly directed towardthe axis of the chamber andterminating in a projectile opening, the projectile openings of saidchambers spaced from each other longitu.

dinally of the device, the walls of each chamber provided with slots forgas escape, each slot of a chamber disposed opposite an imperforate wallportion of another chamber, the slots of the outermost chamber disposedsubstantially above its horizontal axial plane.

13. A compensating device for attachment to the muzzle of firearms toreceive the gases of explosion issuing therefrom, said device comprisinga plurality of coaxial chambers, one chamber within another chamber, theinner chamber attached at its opposite ends to the outer chamber with anappreciable gas receiving area between the walls.ot bothchambers, eachchamberbeing generally cylindrical, the forward end of each chamberhaving its walls inwardly directed toward the axis of the chamber andterminating in a projectile opening, the projectile openings of saidchambers spaced from each other longitudinally of the device andconnected by a projectile receiving tube constituting one of theattachments for the inner chamber, the walls of each chamber providedwith slots for gas escape, each slot of a chamber disposedopposite animperforate wall portion of another chamber, the slots of the outermostchamber disposed substantially above its horizontal axial plane.

14. A compensating device for attachment to the muzzle of rearms and toreceive the gases of explosion as they emerge from the barrel, saiddevice comprising a plurality of coaxial chambers, each chamber boundedby walls forming an enclosure within which the received gases mayexpand, the entire interior surface at the forward end of at least twoof said chambers being forwardly and inwardly directed to receive andresist the impact of the gases moving forwardly therein whereby toincrease the pressure of the expanded gases in each chamber, and

ports in the walls of each chamber for the passage of the gasestherethrough, the ports of said chambers being disposed generallyopposite imperforate wall portions of another chamber.

15. An attachment for the muzzle of rearms having a barrel movable withrespect to the rest of the firearm, said attachment comprising aplurality of substantially coaxial walled chambers, the forward end ofat least two of said chambers having their walls-terminating in anopening establishing a gas seal with the projectile when the projectileis in the opening, one of said chambers having its rearmost wall portionfitted directly upon said barrel, said 'chamber receiving the gases ofvexplosion from said barrel, said chamber having gas outlets in its walladapted to counteract recoil of the firearm when the gas passestherethrough, and an outer chamber having walls attached to a stationaryportion of the firearm and receiving the gases of explosion from aninner chamber, said outer chamber having gas exits in its wall adaptedto produce a predetermined movement of the muzzle of the iirearm whenthe gas passes through said exits.

RICHARD M. CU'I'IS, JR.

